Mobile Intel Pentium 4 Processor - M and Intel 845MP/MZ Chipset Platform Design Guide

Mobile Intel

Pentium

4 Processor-M and Intel

845MP/845MZ Chipset Platform

Design Guide 137

9.10.4.4. 82562ET/82562EM Termination Resistors

The 100-Ω (1%) resistor used to terminate the differential transmit pairs (TDP/TDN) and the 100-Ω

(1%) receive differential pairs (RDP/RDN) should be placed as close to the Platform LAN Connect

component (82562ET or 82562EM) as possible. This is due to the fact these resistors are terminating the

entire impedance that is seen at the termination source (i.e. 82562ET), including the wire impedance

reflected through the transformer.

Figure 70. 82562ET/82562EM Termination

82562ET

Magnetics

Module

RJ45

LAN Interface

Place termination resistors as close to the 82562ET as possible

9.10.4.5. Critical Dimensions

There are two dimensions to consider during layout. Distance ‘B’ from the line RJ45 connector to the

magnetic module and distance ‘A’ from the 82562ET or 82562EM to the magnetic module. The

combined total distances A and B must not exceed 4 inches (preferably, less than 2 inches). See Figure

71 below.

Figure 71. Critical Dimensions for Component Placement

82562EM/

82562ET

ICH2

EEPROM

Magnetics

Module

Line

RJ45

ICH3-M